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Biomedical subjects

J Bergès

Publications and source records attributed to J Bergès.

At least 19 recordsLinked to original sources
PubMed2000

O-H small middle dot small middle dot small middle dotPt(II): Hydrogen Bond with a Strong Dispersion Component.

An MP2 ab initio study of the interaction between a H(2)O molecule and trans-[Pt(OH)(2)(NH(3))(2)] revealed a HO-H small middle dot small middle dot small middle dotPt(II) hydrogen bond (see picture) with a strong dispersion component (ca. 4 kcal mol(-1)). This dispersion interaction is independent of the charge on the complex and is likely to be ubiquitous in aqueous solutions of Pt(II) complexes.

Journal Article↗
PubMed1996

Anchorage-dependent transcription of the cyclin A gene.

NIH 3T3 cells cultured in suspension fail to express cyclin A and hence cannot enter S phase and divide. We show that loss of cell adhesion to substratum abrogates cyclin A gene expression by blocking its promoter activity through the E2F site that mediates its cell cycle regulation in adherent cells. In suspended cells, G0-specific E2F complexes remain bound to the cyclin A promoter. Overexpression of cyclin D1 restores cyclin A transcription in suspended cells and rescues them from cell cycle arrest. In suspended cells, cyclin D1 and cyclin E accumulate normally upon serum stimulation, but their associated kinases remain inactive; their substrates, pRb and p107, are not hyperphosphorylated. Concomitantly, the cyclin-dependent kinase inhibitor, p27KIP1, is stabilized. Ectopic expression of p27KIP1 blocks cyclin A promoter activity through its EN binding site. These data suggest that the block to cyclin A transcription in nonadherent NIH 3T3 cells results from stabilization of p27KIP1 and subsequent inactivation of the specific E2F moiety required for its induction.

3T3 Cells↗
PubMed1995

Cell cycle regulation of the cyclin A gene promoter is mediated by a variant E2F site.

Cyclin A is involved in the control of S phase and mitosis in mammalian cells. Expression of the cyclin A gene in nontransformed cells is characterized by repression of its promoter during the G1 phase of the cell cycle and its induction at S-phase entry. We show that this mode of regulation is mediated by the transcription factor E2F, which binds to a specific site in the cyclin A promoter. It differs from the prototype E2F site in nucleotide sequence and protein binding; it is bound by E2F complexes containing cyclin E and p107 but not pRB. Ectopic expression of cyclin D1 triggers premature activation of the cyclin A promoter by E2F, and this effect is blocked by the tumor suppressor protein p16INK4.

3T3 Cells↗
PubMed1994

Theoretical study of the complexation of amphotericin B with sterols.

The aim of this present work was the study of the intermolecular complexes between amphotericin B (AmB) and either cholesterol or ergosterol. In such complexes the intermolecular interaction energy mainly proceeds from both Van der Waals and H-bonding (via water molecules) forces. Our calculations have shown that the Van der Waals forces slightly favor the AmB-ergosterol complex. Several relative positions of the sterol with regard to AmB lead to energy minima: sterol may be either in contact with the AmB polar head or repelled towards the end of the macrolide ring. It appeared that the role played by some water molecules was to maintain the sterol close to the AmB polar head.

Amphotericin B↗
PubMed1992

Comparative theoretical study of the conformations of amphotericin methyl ester and amphotericin B polar heads in the presence of water.

Amphotericin methyl ester (AmE) is an interesting derivative of amphotericin B (AmB) because of its enhancement of selectivity against the fungicells. Both AmB and AmE molecules differ by the structure of their polar heads. This work deals with a theoretical study of conformations of the polar head of AmE in the presence of hydration water molecules. The results will be compared with our previous work concerning AmB.

Amphotericin B↗
PubMed1976

Alpha 1-antitrypsin activity of perilymph. Occurrence during progression of otospongiosis.

Previous studies by the Adams method demonstrated a strong correlation between hydrolytic enzyme activity of perilymph and progression of bone conduction loss two years preceding stapedectomy. Alpha 1-Antitrypsin was chosen since its activity can be very precisely measured by a radical immunodiffusion technique and since it is one of the enzymes identified in perilymph of patients with active otospongiosis. Samples of 3 mul to 5 mul of perilymph removed during 103 stapedectomies and samples of known alpha 1-trypsin activity were placed on slides coated with alpha 1-antitrypsin serum. The zone of diffusion was stained and measured after 38 hours of incubation. Antitrypsin values were lowest in 24 cases, two with no preoperative bone conduction progression, three with moderate progression of 10 to 15 dB, and 19 with rapid progression of more than 20 dB. They were highest in 36 cases with no progression, and in one case with moderate progression. This study confirms previous reports on the enzymatic activity in otospongiotic disease.

Humans↗
PubMedDate not supplied

[Alpha 2 macroglobulin immunoturbidimetric assays (DakoCytomation reagents) on Roche Diagnostic analysers (Modular P, Cobas Integra). Application to FibroTest-Actic-Test].

BACKGROUND: Alpha2Macroglobulin (A2M) measure showed a revival since it was introduced into FibroTest-ActiTest-Fibro (FT-AT-Fibro) algorithm. More often than not, this assay is performed in immunonephelemetry. Progresses in the comprehension of fibrosis dynamics and better treatment efficacy follow-up will increase FT-AT-Fibro prescriptions. Despite efforts to standardize methods of enzymatic activity measure and proteins measure, we still observe important interlaboratory and intersystem variability. AIM: The primary aim of the study is to validate immunoturbidimetric measure of A2M on Modular P and Cobas Integra analysers (Roche Diagnostics) in utility channel using DakoCytomation reagents in order to extend the analytical system range allowed to measure A2M. The secondary aim of the study is to verify transferability of the six FT-AT composants (A2M, haptoglobin, apolipoprotein A1, total bilirubin, GGT and ALT) to Roche Diagnostics equipment by comparing with results measured on the reference system. RESULTS: A2M measures (n = 146) showed linearity, repetitiveness and were reproducible. Readjustments to adapt A2M measures were required. A corrector factor of 0.84 for Modular P and of 0.87 for Cobas Integra was introduced in order to readjust the immunoturbidimetric method to the immunonephelemetric method. The rationale of proposed corrector factors is based on the use of Dade Behring and DakoCytomation reagents (antisera and calibrant). Biologist vigilance is required to point out modifications or variations in reagents that could be done by the company. The six parameters results transferability from the reference system to Roche Diagnostics was demonstrated by statistic analysis. FT-AT showed excellent correlations to the reference system for Modular P and Cobas Integra analysers. In this study no difference more than 0.11 was recorded and only few subjects had differences between 0.05 and 0.10. Therefore this very low inter-analysers variability has no significant clinical impact. CONCLUSION: This study showed that the analytical system made of Modular P, Cobas Integra, Roche Diagnostics and DakoCytomation reagents can be used for FibroTest-ActiTest-Fibro parameters assessment. Their statistical and clinical variability were acceptable compared to the reference system.

Automation↗